1. Field of the Invention
The present invention is related to a voltage regulator circuit and particularly to a multi-stage voltage regulating circuit with automatic thermal compensation and a multi-stage voltage regulating method thereof.
2. Brief Description of the Related Art
The voltage regulator circuit is used for supplying the power required by a liquid crystal display panel. Because a gate-on voltage of the thin film transistor (TFT) in the liquid crystal display panel increases with a decreasing temperature, the voltage of the power of the liquid crystal display panel has to be increased in order to maintain a normal operation of the liquid crystal display panel in an environmental of low temperature. However, it causes that the function of the liquid crystal display panel becomes ineffective after the operation temperature being increased although increasing the voltage of the power is able to solve the problem of starting the liquid crystal display panel at the low temperature.
In order to solve the problem of ineffectiveness of the function of the liquid crystal display panel, conventionally, the boost-type voltage regulating circuit with automatic temperature compensation as shown in FIG. 1 or the fixed-mode charge-pump type voltage regulating circuit with automatic temperature compensation as shown in FIG. 2 is employed to supply the power of the liquid crystal display panel so as to lower the output voltage of the power after the liquid crystal display panel being in a state of normal operation and the operation temperature increasing for improving the deficiency of the ineffective function.
Nevertheless, the boost-type voltage regulating circuit with automatic temperature compensation as shown in FIG. 1 needs components such as inductors and power transistors to result in that it is hard to lower the cost of the voltage regulating circuit; the fixed-mode charge-pump type voltage regulating circuit with automatic temperature compensation as shown in FIG. 2 is merely capable of regulating the voltage in a fixed range such that the improved function is limited significantly.